Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

649
FXUS63 KLOT 021148
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
648 AM CDT Thu Jul 2 2026

.KEY MESSAGES...

- Hot and humid conditions will continue into the holiday
  weekend, with peak heat index values around 105 degrees today
  and around 100 degrees Friday and Independence Day.

- Waves of thunderstorms are expected through the weekend. With
  that said, there will be many dry hours. Any thunderstorms on
  Friday will be capable of producing damaging winds.

&&

.DISCUSSION...
Issued at 300 AM CDT Thu Jul 2 2026

Hot and humid conditions will persist today, and possibly over
some or all of the forecast area on Friday. Slight mixing of dew
points across a weakening cap today should keep dew points in
the low to possibly mid 70s. With temps expected to peak in the
low to mid 90s, today will feature another afternoon with heat
index values in the 100 to 105 degree range. Maintained the
current Extreme Heat Warning through this evening, though some
consideration of an extension through Friday will be needed for
at least the southern half of the forecast area depending on the
expected outcome of convection tonight into Friday morning.

As of 3AM, elevated convection continues to develop across
central Wisconsin along a generally WSW to ENE corridor.
Remaining capping farther south has resulted in a notable
southern terminus of the convection from the northern Milwaukee
metro to far northeast Iowa. A resultant outflow has started to
show some slowing with its southward trek toward the state line,
but should shift far enough south to disrupt the low-level wind
field for a few hours across the northern tier of counties in
northern Illinois early this morning. With recent convection
struggling to extend farther south, concerns for new convection
along this outflow boundary are waning with time. However, have
maintained a slight chance of showers and storms over these
northern counties through mid-morning.

Under the expectation that little to no convection occurs over
northern Illinois through the daytime hours, the first favored
window for storms will be very late this evening into the
overnight hours. A mid-level wave emanating from eastern
Colorado early this morning as evident by WV imagery and
associated downstream convection may go through a couple
iterations of convective enhancement over the next 24 hours as
it tracks toward central Wisconsin through this evening. It
appears likely that a (potentially) organized cluster of
convection will develop somewhere around the NE/IA line by early
evening and focus along a residual outflow from current
convection. With the ongoing de-amplification of the mid-level
ridge and substantially less capping over the area by this
evening, any well formed MCS could survive into southern
Wisconsin and northern Illinois late this evening into the
overnight hours. However, convection would likely become cold
pool dominant with southward extent as stronger shear/mid-level
flow remain farther north over Wisconsin. With that said, a
stronger cold pool surging into the antecedent warm and humid
airmass implies a potential for strong to locally damaging winds
into portions of northern Illinois.

A more potent wave currently crossing northern Arizona will
become another focus for convection over our area on Friday.
This wave will cross southern Wisconsin mid to late afternoon,
setting the stage for a potential line of convection in the area
later Friday afternoon into the evening. If convection
materializes tonight, there will likely be a notable outflow
boundary stalled over the forecast area Friday morning that
could complicate the forecast by altering the location of
convective initiation. Meanwhile, no convection tonight would
lead to a fairly untapped and uncapped airmass over the area
through the entire day. While these differences introduce a
decent amount of uncertainty regarding the timing and location
of convection, late afternoon through mid-evening Friday appear
to have the greatest chance for at least a broken line of
storms over northern Illinois and northern Indiana. Modest deep
layer shear and an inherent high DCAPE reservoir with the
warm/humid airmass support the risk for damaging winds with any
linear segment or multicell clusters.

A mid-level impulse exiting the northern Rockies late on Friday
will provide renewed convective episodes in the region as the
mid-level pattern becomes zonal. The track of this convection
will likely focus along an effective cold front produced by the
combined effects of convection over the next 48 hours. So while
convection seems likely in the region on Saturday/Independence
Day, the location of convection could range from southern
Wisconsin to southern Illinois. Furthermore, with forecast
guidance consistently depicting a slowing or stalling mid-level
wave over the western Great Lakes late Saturday into early next
week, timing out precip chances becomes even more difficult if
not impossible.

As the aforementioned wave eventually drifts eastward, drier
and somewhat cooler conditions are expected by the middle of
next week.

Kluber

&&

.AVIATION /12Z TAFS THROUGH 18Z FRIDAY/...
Issued at 648 AM CDT Thu Jul 2 2026

Decaying convection over southern Wisconsin this morning has
pushed a stout outflow boundary southward toward the terminals,
with a N/NNE wind shift and brief gusts to 20 knots affecting
all terminals by 13Z. A band of BKN MVFR ceilings will also
trail the outflow boundary for an hour or two. Precip is not
expected to affect the terminals, though a couple SHRA could
near ORD/DPA to the north through mid morning.

VFR conditions will prevail late this morning through sunset.
N/NNE winds associated with the outflow are expected to veer SW
with gusts over 20 knots by late morning. SW winds around 10
knots should then persist tonight through Friday morning.

A mid-level wave over western Nebraska and Kansas this morning
is expected to generate a cluster of TS over the Missouri River
Valley by early evening. This cluster of TS may track across
southern Wisconsin and perhaps well into northern Illinois very
late this evening and especially overnight. Gusty winds could
accompany any TS. Additionally, any substantial coverage of TS
would disrupt the low-level wind field and yield VRB, or more
likely, winds with an easterly component toward daybreak
Friday.

Kluber

&&

.CLIMATE...
Issued at 300 AM CDT Thu Jul 2 2026

....Daily Records for the Week........

Chicago (KORD)
            Record High       Record Warm Minimum
July 2        99 (1970)            79 (1911)
July 3       102 (1949)            78 (1911)
July 4       102 (2012)            80 (1921)


Rockford (KRFD)
            Record High       Record Warm Minimum
July 2        99 (1910)            74 (1970)
July 3        99 (1925)            75 (2012)
July 4       102 (2012)            77 (1977)

NWS Chicago

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Extreme Heat Warning until midnight CDT tonight for ILZ003-
     ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-ILZ012-ILZ013-
     ILZ019-ILZ020-ILZ021-ILZ023-ILZ032-ILZ033-ILZ039-ILZ103-
     ILZ104-ILZ105-ILZ106-ILZ107-ILZ108.

IN...Extreme Heat Warning until midnight CDT /1 AM EDT/ tonight for
     INZ001-INZ002-INZ010-INZ011-INZ019.

LM...None.

&&

$$

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